1. Field of the Invention
The present invention relates to a semiconductor module such as a power semiconductor module having a plurality of semiconductor elements in a single package.
2. Description of the Related Art
FIG. 12A is a perspective view of a conventional semiconductor module 100 for motor drive control containing a plurality of power semiconductor elements, for example, insulated gate bipolar transistors (IGBTs). This semiconductor module 100 comprises a metallic base plate 20, an insulated circuit board 21 on the base plate 20, and a plurality of power semiconductor elements 22 fixed at predetermined positions on the insulated circuit hoard 21 with solder as shown in FIG. 4. The semiconductor module 100 further comprises metallic main terminals 102, control terminals 103, and a resin case 104 that is a frame for protecting the power semiconductor elements 22 and for fixing the main terminals 102 and the control terminals 103 that are leading out of the housing. The space in the resin case 104 is filled with a resin composite in a gel stale. The power semiconductor elements are mounted on a metallic circuit pattern formed on the insulated circuit board 21 and connected with aluminum wires 23 between the metallic circuit pattern and metallic electrodes on the semiconductor elements 22.
FIG. 8 shows an equivalent circuit of a semiconductor module composed of semiconductor elements of IGBTs T1 and T2 and free wheel diodes (FWDs) D1 and D2 reverse-parallel-connected to the IGBTs T1 and T2, respectively. A resin composite in a gel state is filled in a space between the resin case 104 and a bottom plate that is the metallic base plate 20 for mounting these power semiconductor elements 22. The metallic main terminals 102, which are a C1 terminal, an E2 terminal, and a C1E2 terminal as shown in FIG. 12A, are connected externally through a screw holes 105 formed in the metallic main terminals 102 exposing to the center surface of the resin case 104. The auxiliary terminals 103, which are a g1 terminal, an e1 terminal, an e2 terminal, and a g2 terminal, are led out through the slits 106 formed in the end region of the surface of the resin case 104. The metallic base plate 20 has four holes for attaching itself to a heat sink at the corners of the base plate 20. The resin case 104 has an opening at the bottom thereof for the resin case 104 to be fitted to the base plate.
Patent Document 1 discloses a semiconductor device in which electrode terminals are ensured to be held on a thermoplastic resin housing to enhance reliability in assembling quality, and the electrode terminals are prevented from falling off from the resin housing due to vibration.
Patent Document 2 discloses a semiconductor module that includes a resin case, connection elements for external main connections and control connections, and an insulated substrate with a metallized surface. The insulated substrate mounting semiconductor elements is inserted into a bottom opening of the resin case.
Patent Document 3 discloses a semiconductor module with a high dielectric strength and high reliability in which a control terminal has a projecting portion at a position of passing through the resin case and an L-shaped portion is provided in the control terminal in order to avoid transmission of stress onto the insulated circuit board in attaching and detaching processes of a connector.
[Patent Document 1]
Japanese Utility Model Application Publication No. H05-006852 (Abstract and FIG. 1, in particular)
[Patent Document 2]
U.S. Pat. No. 6,597,585 (claim 1 and FIG. 3, in particular)
[Patent Document 3]
WO2012/0066833 pamphlet (Abstract and FIG. 1, in particular)
In the semiconductor module 100 shown by the perspective view of FIG. 12A, the resin injected in the resin case 104 is a resin composite in a gel state exhibiting flexibility that cannot rigidly fix the leading out terminals of the metallic main terminals 102 and the control terminals 103. Thus, the leading out terminals need to be fixed at the openings in the resin case 104 formed for leading out the terminals. Of the leading out terminals, the metallic main terminals 102 are held with the resin housing 104 and thus, the stress exerted in the processes of external connection is scarcely transmitted to the bottom portion of the main terminal.
As for the auxiliary terminals 103, however, after fixing the auxiliary terminals 103 onto the insulated circuit board 21, the auxiliary terminals 103 need to be easily inserted through the openings 107 for the auxiliary terminals formed in the resin case 104 and also to be securely held on the housing. To meet these requirements, the openings 107 for the auxiliary terminals, as shown in FIG. 12A, each have a configuration of a slit with a size that is slightly larger than the cross-sectional size of the terminal. In addition, the auxiliary terminal 103 is provided with a projecting portion and the resin case is provided with a notch to hold the terminal on the housing as shown in FIG. 12B. In FIG. 12B, the references 104a and 104b designates partial cross-sections of the resin case. The auxiliary terminals 103 each have a projecting portion 103a inside the resin case 104, and the resin case 104 has a recess 108 corresponding to the projecting portion 103a. The recess 108 restricts vertical movement of the projecting portion 103a. In the method of holding the terminals utilizing the projecting portion and notch, however, the terminals become easily disengaged in the longitudinal direction of the slit because the slit is formed with a little larger dimension. This is the case wherein an external force is exerted toward the left at the upper position of the auxiliary terminal 103 in FIG. 12B. If the slit length is decreased to avoid disengagement of the auxiliary terminal, insertion can be hardly carried out, and some stress may be exerted on the bottom portion of the auxiliary terminals in the inserting process. Thus, the reduction of the slit length is limited.